Replacement ceramic cartridge ...

background ... I have a tub which fills via the "overflow" and has a hand-held sprayer as well. The water temp, volume and direction (ie fill or spray) is controlled via a stand alone unit/valve/control whatever. It developed a "stem" leak - not major, but continuous. With help, I dissembled the unit and found a ceramic cartridge - the only identification on it being "SEDAL" and a date of manufacture. BTW, the valve is totally anonymous - no name/number etc anywhere. I was given an identical replacement at a Home Depot (nb in a plastic bag, not original packaging) as the unit supposedly has a lifetime warranty. This "new" cartridge leaked worse than the original ... RATS!! Finally, my question ... any suggestions as to where I can buy a new, in the box, SEDAL ceramic cartridge? I suspect that as long as the inlets/outlet line up with the holes in the valve body (and the locating pins are the same) it should work. Would silicone on the existing gasket work? (allowing 24 hours to "set" before testing, that is? Any ideas (and/or sympathy) appreciated Bob